Most don't take it and yet again you're not presenting objective facts.
Also look at hairloss forums and reddit to see how many men that KNOWS about the available treatments but still don't want to commit to something simple as Minoxidil. They want something magical that doesn't require any effort and have no possible side effects.
Most men don't care enough to even look into treating their hairloss.
In the US alone there were just under 10 million prescriptions for Finasteride for 2019. Now take into consideration that it would only be used mainly by men and furthermore, men usually between the ages of approximately 20 to below 65 (most often), which is approximately 100 million men in the US according to statista.com
Then we know that only approximately 50 - 60% of men experience hairloss, that leaves us with approximately 50 - 60 million men in the US who are experiencing hairloss between that age group.
When you consider this, it does make up a significant percentage of the male population in the country that are using Finasteride, and it definitely is NOT only a few dozen in a million, that's completely far off.
So as I said, if Finasteride was even remotely as effective as they claim, there would be a significant % of men between 20 to 65 years old with good heads of hair which are not progressively getting worse, which is obviously not the case.
Sure I know some people don't use hair treatments, it's usually the older men who don't know any better, but for the younger generation below 60 years old that are also fairly well versed with the internet, they know very well that there are treatments for Hairloss.
Thinking people don't know they are hairloss treatments is naive, because people when they have the flu literally Google their symptoms and check for remedies. Do you seriously think they wouldn't do the same for a far more important physical feature which makes up a big part of their physical appearance? Of course not. People who lose hair also address it with at the bare minimum a doctor consult, if not a dermatologist at some point in their life who would tell them what their treatment options are.
It's more often that people who don't use treatments have once tried a hairloss treatment like Finasteride and found it to be ineffective and/or cuases sides and stop us, after which point they say things like "it's not worth the effort".